| Bamboo shoot, the young stems of bamboo, is a kind of common vegetables for centuries in China. Phyllostachys pubescens, which is widely distributed in China, is the main bamboo of producing bamboo shoot. Canned bamboo shoot is the main commercial product besides fresh edible. Traditional canned bamboo shoots are usually made from fresh bamboo shoot with shelled, rinsed, cooked, canned and sterilized. Large pot of canned bamboo shoot often made into small package besides directly into circulation. This process also is prone to cause serious environmental pollution, with excess boiled liquids of bamboo shoots.In this work, our attention has been focused on the functional ingredients in boiled water of bamboo shoots, filled liquid, squeezed juice (collectively referred abstract of bamboo shoot, called AEBS in our study). We focused on AEBS, which is rich in active peptides, amino acid, polysaccharide, flavonoids and phenolics, and aimed to dig out certain natural ingredients beneficial to human health. Bamboo shoot peptides were undergone systematic chemical, technology and functional studies, in order to utilize bamboo shoots in more reasonable way. The functional roles in reducing blood lipid and lowering blood pressure of bamboo shoot peptides were investigated, with main results summarized as follows.1) The pretreatment of AEBS was collected which is rich in amino acid (21.32±1.16g/100g, dry basis), polysaccharide (13.17±0.98g/100g, dry basis), total flavonoids (1.41±0.12g/100g, dry basis) and phenolic acids (4.78±0.24g/100g, dry basis). We selected active section, which was rich bamboo shoot peptides, using angiotensin converting enzyme (ACE, EC3.4.15.1) inhibitoiy activity and anti-oxidant system (DPPH·, ABTS·+, FRAP) as indicators. Ultra-filtration of membrane cut-off technology and macroporous resin DA201-C enrichment technology were applied, in order to enrichment active ingredients. During this process bamboo shoot ACE inhibitory preparation (BSP) and crude polysaccharide were obtained. Crude polysaccharide was obtained by ethanol precipitation from molecular weight cut-off membrane more than10KDa, which was the combination compound of phenolic components and polysaccharide polymers.2) Crude polysaccharide polymer was hydrolysated under acid and alkali condition, respectively. The results come out that total flavonoids contents didn’t exhibit significant differences before and after the hydrolysis. However, total phenolics contents were higher in the sample after acid hydrolysis, particularly for the content of p-coumaric acid and ferulic acid, which may cause by the decomposition of phenolic components and polysaccharide polymer during the acid hydrolysis. Furthermore, total phenolics contents were significantly positively correlated with the antioxidant and ACE inhibitory activities, which was the reason that the sample of acid hydrolysis exhibited the better antioxidant and higher ACE inhibitory activities compared with crude sample and hydrolysated sample under alkali condition.3) Fractional extraction of ethyl acetate and n-butanol was applied to separate bamboo shoot ACE inhibit peptides. The result come out that the left water fraction exhibited the highest ACE inhibitoiy activity. All fractions, including ethyl acetate fraction (BSME), n-butanol fraction (BSMB) and the water fraction (BSML), were evaluated by antioxidant capacities. Results indicated that antioxidant capacities were related to total flavonoids contents, while ACE inhibitory activity was related to the content of peptides. P2, which possessed higher ACE inhibitory activity, was obtained though Sephadex G-15gel and purified further by semi-preparative reversed-phase high performance liquid chromatography. The active fraction P2-2was obtained, key component of which was dipeptide with effective sequence detected to be Asp-Tyr-by UPLC-ESI-MS.4) BSP is rich in high contents of amino aicds (42.78±5.75g/100g), total flavonoids (5.07±0.47g RE/100g), phenolic acids (10.91±0.98g GAE/100g). Experiment was applied to investigate the effect of BSP on improving the cardiovascular status and oxidative stress status in hyperlipidemic rats. Results showed that350mg/day kg BW BSP administration could significantly reduce content of total cholesterol (TC), triacylglycerol (TG), low-density lipoprotein cholesterol (LDL-c) in the serum of hyperlipidemia rats, the atherosclerosis index (AI) and fatty acid synthase (FAS) in Liver.200mg/day kg BW BSP administration could effectively reduce the content of TC, TG and LDL-c in the liver of hyperlipidemia rats, while100mg/day kg BW BSP administration could only reduce content of TC in the liver of hyperlipidemia rats. All administration groups could significantly increase the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), and reduce content of malonaldehyde (MDA), which meaned that the oxidative stress status had been alleviated.5) Spontaneously hypertensive rats (SHR) was applied as test model for evaluation the biology effect of BSP. In the (0～8h) experiment of anti-hypertension in SHR,100mg/day kg BW BSP exhibited equivalent effect to10mg/day kg BW Captoril after4h～6h administration.50mg/day kg BW BSP exhibited equivalent effect to10mg/day kg BW synthetic peptides. Based on above test,4weeks experiment of BSP regulation blood pressure was carried out: SHR control group (distilled water), positive control group (Captopril,10mg/day kg BW), BSP (50mg/day kg BW), BSP (100mg/day kg BW), Combined group of BSP and bamboo shavings (EZR2002)(BSP50mg/day kg BW+EZR200250mg/day kg BW).The blood pressure of SHR decreased after7d BSP (50mg/day kg BW,100mg/day kg BW) administration, compared with control group. BSP (50mg/day kg BW,100mg/day kg BW) could inhibit ACE activity in lung and in serum with dose effective. The combination of BSP50mg/day kg BW and EZR200250mg/day kg BW showed excellent effect on anti-hypertensive and inhibited ACE activity in lung of SHR (p<0.01) and in the serum (p<0.01).The oxidative stress status was evaluated. Synthetic peptide could significantly increase the serum GSH-Px activity (p<0.05) of SHRs. BSP (50mg/day kg BW,100mg/day kg BW) could increase the activities of serum SOD, GSH-Px, NO, NOS in kidney and total anti-oxidant capaticy in liver with dose effective. The combination of BSP50mg/day kg BW and EZR200250mg/day kg BW showed excellent effect on oxidative stress status:increase the activities of serum SOD (p<0.01), GSH-Px (p<0.01), NO(p<0.01), NOS in kidney (p<0.01), MDA contents both in the serum (p<0.01)and liver (p<0.01).In conclusion, BSP and EZR2002derived from bamboo secondary metabolites exhibited prominent capacity to improve oxidative stress status in hyperlipidemic rats and SHRs. The antihyperlipidemic effect was attributed to phenolic compounds via FAS inhibition. Antihypertension experiment effect contributes to ACE inhibition and improving NO level. Howerver, the regulation mechanism and related signal pathways need further research and investigation. The active ingredients were enrichment by combination of ultra-filtration of cut-off membrane technology and macroporous resin DA201-C technology, which could provide reference for further utilizatin of by-product from canned bamboo shoot industry. |
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